Learn Enough JavaScript to Be Dangerous

Michael Hartl created the legendary Ruby on Rails™ Tutorial that helped jumpstart thousands of web development careers. A cofounder and principal author at Learn Enough, Hartl previously earned a Ph.D. in physics at the California Institute of Technology (Caltech), where he received a Lifetime Achievement Award for Excellence in Teaching. He is also an alumnus of Harvard University and the world-renowned Y Combinator entrepreneur program.

• Preface xiii About the Author xvii Chapter 1: Hello, World! 1 1.1 Introduction to JavaScript 5 1.2 JS in a Web Browser 7 1.3 JS in a REPL 14 1.4 JS in a File 21 1.5 JS in a Shell Script 22 Chapter 2: Strings 25 2.1 String Basics 25 2.2 Concatenation and Interpolation 27 2.3 Printing 33 2.4 Properties, Booleans, and Control Flow 35 2.5 Methods 44 2.6 String Iteration 50 Chapter 3: Arrays 55 3.1 Splitting 55 3.2 Array Access 56 3.3 Array Slicing 58 3.4 More Array Methods 59 3.5 Array Iteration 62 Chapter 4: Other Native Objects 65 4.1 Math and Number 65 4.2 Dates 69 4.3 Regular Expressions 73 4.4 Plain Objects 81 4.5 Application: Unique Words 83 Chapter 5: Functions 91 5.1 Function Definitions 91 5.2 Functions in a File 95 5.3 Method Chaining 104 5.4 Iteration for Each 110 Chapter 6: Functional Programming 115 6.1 Map 116 6.2 Filter 122 6.3 Reduce 126 Chapter 7: Objects and Prototypes 135 7.1 Defining Objects 135 7.2 Prototypes 139 7.3 Modifying Native Objects 147 Chapter 8: Testing and Test-Driven Development 153 8.1 Testing Setup 154 8.2 Initial Test Coverage 159 8.3 Red 164 8.4 Green 172 8.5 Refactor 177 Chapter 9: Events and DOM Manipulation 187 9.1 A Working Palindrome Page 187 9.2 Event Listeners 192 9.3 Dynamic HTML 202 9.4 Form Handling 205 Chapter 10: Shell Scripts with Node.js 215 10.1 Reading from Files 216 10.2 Reading from URLs 218 10.3 DOM Manipulation at the Command Line 224 Chapter 11: Full Sample App: Image Gallery 235 11.1 Prepping the Gallery 235 11.2 Changing the Gallery Image 242 11.3 Setting an Image as Current 250 11.4 Changing the Image Info 252 11.5 Conclusion 259 Index 263

Praise for Learn Enough Tutorials "I have nothing but fantastic things to say about @LearnEnough courses. I am just about finished with the #javascript course. I must say, the videos are mandatory because @mhartl will play the novice and share in the joy of having something you wrote actually work!" --Claudia Vizena "I must say, this Learn Enough series is a masterpiece of education. Thank you for this incredible work!" --Michael King "I want to thank you for the amazing job you have done with the tutorials. They are likely the best tutorials I have ever read." --Pedro Iatzky